1. Field of the Invention
The invention relates in general to a Balun circuit, and more particularly to a Balun circuit manufactured by integrate passive device (IPD).
2. Description of the Related Art
Generally speaking, after a wireless signal is received by the antenna of a communication device, the single-port signal outputted from the antenna will be outputted to a Balun circuit. The Balun circuit will transform the single-port signal into a dual-port signal, and further output the dual-port signal to a radio frequency (RF) transceiver for processing.
One of the currently available Balun circuits is manufactured by low temperature co-fired ceramic (LTCC) process. However, the Balun circuit manufactured by LTCC process must be electrically connected to a substrate through surface-mount technology (SMT) first before the Balun circuit manufactured by LTCC process can be electrically connected to the RF transceiver chip on the substrate. Thus, the substrate must have a reserved region for the disposition of the Balun circuit manufactured by LTCC process and a reserved region for the disposition of the RF transceiver chip. To meet the above requirements, the substrate must have a larger area which occupies a larger space in the communication device. Thus, how to reduce the required area of the substrate so as to save the internal space of the communication device has become one of the important directions to the manufacturers.